Warren, Graham James (1988) Low field transport properties of a GaAs/Ga[sub]1-xAl[sub]xAs superlattice. PhD thesis, University of Warwick.

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Abstract

This thesis presents some low field mobility, thermopower and Hall factor results for a GaAs/Gai-xAlxAs superlattice. For these calculations, acoustic phonon scattering and polar optic phonon scattering are considered. For the acoustic phonon calculation, the zero magnetic field Boltzmann equation is solved using the relaxation time approximation to give the mobility and thermopower results. The thermopower results show a positive peak which is a direct consequence of the small scale of the structure of the superlattice. The polar optic phonon results are obtained using both the relaxation time approximation, which is not strictly valid in this case, and also by an exact numerical iterative method. This shows the relaxation time mobility results to be less than the exact numerical solution by up to a factor of about two. This is due to the inelasticity of the scattering mechanism and the anisotropic nature of the miniband structure.

The Hall factors are calculated using a novel method. Using this method, it is not necessary to solve the non-zero magnetic field Boltzmann equation. Instead, the zero magnetic field Boltzmann equation is solved for two perpendicular orientations of applied electric field, and these zero magnetic field distribution functions are then used to simply calculate the Hall factors. The deviations of the resulting Hall factors from one can give direct information about the form of the miniband structure. Some simple analytical calculations are used to complement the numerical results.

Item Type:	Thesis (PhD)
Subjects:	Q Science > QC Physics
Library of Congress Subject Headings (LCSH):	Superlattices as materials, Semiconductors
Official Date:	September 1988
Dates:	Date Event September 1988 UNSPECIFIED
Institution:	University of Warwick
Theses Department:	Department of Physics
Thesis Type:	PhD
Publication Status:	Unpublished
Supervisor(s)/Advisor:	Butcher, Paul N.
Format of File:	pdf
Extent:	[4], 88 leaves : illustrations
Language:	eng

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